How did we get here?

Trying to understand variables behind Okanagan Valley flooding

Sean Reimer’s task as the water level manager for Okanagan Lake is to try to strike a balance.

Reimer attempts to manage the water use conflicts by potential prognosis while relying on weather forecasting science that is anything but exact.

So when that balance objective goes awry, as it has this spring with widespread flooding around the Okanagan Lake foreshore, Reimer finds himself in the unenviable position of being a scapegoat for the stress and heartache felt by flood victims this.

“It’s like my kids say, ‘Dad, you are only in the news when things are tough out there.’ It’s not so much fun being in my position but I’ve appreciated the response I’ve received to be quite frank,” Reimer said.

“For so many years now we have not had a problem managing the lake level so I like it when you don’t have to hear from me.”

At this point, trying to analyze what happened, he says, is really delving into the unknown: Trying to understand how projected drought conditions back in January for the spring evolved into Okanagan Lake being 72 centimetres above its projected depth . It was an unexpected combination of weather factors that struck from mid-April through the beginning of May.

And in the centre of that decision-making process was Reimer, having to take into consideration what potential spring drought conditions would have on the kokanee spawning water needs along the shoreline in Okanagan Lake, and the spawning needs of the sockeye salmon run in the Okanagan River, the largest in the Columbia River basin system.

Speaking at a flood recovery forum hosted by the District of Lake Country last week, Reimer said he was not there to make excuses, only to explain the decision-making process that unfolded. It was a talk he will undoubtedly be called upon to make in other communities such as Kelowna, Penticton and West Kelowna in the weeks ahead as the flooding crisis subsides.

Coming into March, Reimer said the drought scenario appeared to be falling into place, before a combination of record precipitation in some areas and further snowpack build-up began to change that projection considerably.

“Penticton had a record high amount of precipitation for the March-April-May period, Kelowna had the second wettest ever and Vernon recorded its fourth wettest,” he said.

The unknown factor that environment and weather forecasters are still trying to understand better was the saturation level of the ground.

Reimer said in October, November and leading into December, snow had not yet arrived in the higher elevations. Instead there was precipitation.

The snowfall eventually came, covering the saturated ground. Come spring, with that saturation in place with the spring thaw, there was little ground-level absorption of the melting snow.

Meanwhile, the humidity in the air leading up to the early May storm event that triggered the start of flooding was unusually high.

Normally the air moisture dew point level in spring is below zero degrees, and when the May 4 storm hit, the dew point was 15 and 16 degrees, which is very rare, according to Environment Canada meteorologist Doug Lundquist.

So instead of snowmelt-sourced moisture evaporating into the atmosphere, it was condensing into water, combining with the snowmelt and underground water flows to create a perfect storm of flood conditions.

“That is something I will be interested to look at going forward but the problem is we’ve had ground saturation levels in the past, why did it not contribute in the same way to the flooding problems we’ve seen this spring?” Reimer is left to consider.

One thing that Reimer does know, contrary to what many speculate, was the U.S. being to blame for the flooding by withholding overflow water from crossing the Oroville dam at Osoyoos Lake into Washington. That is not the case he said.

“There are no flow issues for us with the Americans. We are not required to stop or hold back water or send water down either. We send down what we send down, and that’s it,” Reimer said, reiterating that the water release capacity at the Penticton dam is a more key limiting factor.

And that comes back to many who argue Reimer should have released more water earlier in late winter, something hindsight suggests makes sense but the data collection didn’t support at the time.

“My explanation isn’t going to satisfy everyone. This is very personal for people affected by the flooding and I get that,” Reimer said.

“But it’s important to understand what drove the decisions made was the information, the data that was available to use at that time.

“We are left to wonder about the extent of the inflows to (Okanagan Lake) this year, which were historic, and hope to get a better understanding of the groundwater impact created by the high soil saturation level. Ideally, it would be helpful if we could get a weather forecast three weeks out that was 100 per cent accurate but that will never happen.”